Io HD + G5

Hi I've done a search but haven't found a definitive answer. I'd like to know whether Io HD will work with a G5 dual 2Ghz machine? I've got an HD job coming up for NatGeo and it appears that they require a minimum compression spec of prores 220. It's going to be shot on HDcam So if the Io does all the encoding and decoding the G5 should be fine shouldn't it? It's stuffed with RAM and SCSI storage and I'd like it to live on a bit longer.

However if in the real world if it's going to be deadly slow then I might have to reconsider. Is anybody out there working like this?